1. Field of the Invention
This invention relates to a mask for selectively transmitting therethrough a desired light radiant energy and more particularly, to a mask comprising a copolymer of tetrafluoroethylene and hexafluoropropylene.
2. Description of the Prior Art
Presently, several techniques for electroless metallization of a surface involve selective light radiation exposure of a pretreated or sensitized surface. For example, U.S. Pat. No. Re. 29,015; U.S. Pat. Nos. 3,772,078 and 3,907,621 disclose such an exposure.
When such techniques are employed as well as any selective photoimaging technique, problems occur with the photomasks which are employed. Typically, quartz masks are employed which are expensive. Additionally, masks, such as quartz masks, are not conforming to irregularities of the surface being masked, thereby leading to problems of non-registry or misregistry as well as poor fine line resolution. Masks having flexible polymeric bases have been employed but these masks suffer from the disadvantage of a variance in their dimension under the influence of temperature and/or humidity in the ambient atmosphere as well as an undesired expansion or contraction due to the heat generated from the light source employed to image a surface.
A photomask which is relatively inexpensive and having excellent thermal dimensional stability, hygroscopic dimensional stability, dimensional stability on standing and the like is needed and is desired.